Add libgmp 6.2.0 to third_party
Don't build it yet. That will come in the next review.
Change-Id: Idf3266558165e5ab45f4a41c98cc8c838c8244d5
diff --git a/third_party/gmp/mpn/generic/invert.c b/third_party/gmp/mpn/generic/invert.c
new file mode 100644
index 0000000..157ff2b
--- /dev/null
+++ b/third_party/gmp/mpn/generic/invert.c
@@ -0,0 +1,86 @@
+/* invert.c -- Compute floor((B^{2n}-1)/U) - B^n.
+
+ Contributed to the GNU project by Marco Bodrato.
+
+ THE FUNCTIONS IN THIS FILE ARE INTERNAL WITH MUTABLE INTERFACES. IT IS ONLY
+ SAFE TO REACH THEM THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST
+ GUARANTEED THAT THEY WILL CHANGE OR DISAPPEAR IN A FUTURE GMP RELEASE.
+
+Copyright (C) 2007, 2009, 2010, 2012, 2014-2016 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP Library is free software; you can redistribute it and/or modify
+it under the terms of either:
+
+ * the GNU Lesser General Public License as published by the Free
+ Software Foundation; either version 3 of the License, or (at your
+ option) any later version.
+
+or
+
+ * the GNU General Public License as published by the Free Software
+ Foundation; either version 2 of the License, or (at your option) any
+ later version.
+
+or both in parallel, as here.
+
+The GNU MP Library is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+for more details.
+
+You should have received copies of the GNU General Public License and the
+GNU Lesser General Public License along with the GNU MP Library. If not,
+see https://www.gnu.org/licenses/. */
+
+#include "gmp-impl.h"
+#include "longlong.h"
+
+void
+mpn_invert (mp_ptr ip, mp_srcptr dp, mp_size_t n, mp_ptr scratch)
+{
+ ASSERT (n > 0);
+ ASSERT (dp[n-1] & GMP_NUMB_HIGHBIT);
+ ASSERT (! MPN_OVERLAP_P (ip, n, dp, n));
+ ASSERT (! MPN_OVERLAP_P (ip, n, scratch, mpn_invertappr_itch(n)));
+ ASSERT (! MPN_OVERLAP_P (dp, n, scratch, mpn_invertappr_itch(n)));
+
+ if (n == 1)
+ invert_limb (*ip, *dp);
+ else if (BELOW_THRESHOLD (n, INV_APPR_THRESHOLD))
+ {
+ /* Maximum scratch needed by this branch: 2*n */
+ mp_ptr xp;
+
+ xp = scratch; /* 2 * n limbs */
+ /* n > 1 here */
+ MPN_FILL (xp, n, GMP_NUMB_MAX);
+ mpn_com (xp + n, dp, n);
+ if (n == 2) {
+ mpn_divrem_2 (ip, 0, xp, 4, dp);
+ } else {
+ gmp_pi1_t inv;
+ invert_pi1 (inv, dp[n-1], dp[n-2]);
+ /* FIXME: should we use dcpi1_div_q, for big sizes? */
+ mpn_sbpi1_div_q (ip, xp, 2 * n, dp, n, inv.inv32);
+ }
+ }
+ else { /* Use approximated inverse; correct the result if needed. */
+ mp_limb_t e; /* The possible error in the approximate inverse */
+
+ ASSERT ( mpn_invert_itch (n) >= mpn_invertappr_itch (n) );
+ e = mpn_ni_invertappr (ip, dp, n, scratch);
+
+ if (UNLIKELY (e)) { /* Assume the error can only be "0" (no error) or "1". */
+ /* Code to detect and correct the "off by one" approximation. */
+ mpn_mul_n (scratch, ip, dp, n);
+ e = mpn_add_n (scratch, scratch, dp, n); /* FIXME: we only need e.*/
+ if (LIKELY(e)) /* The high part can not give a carry by itself. */
+ e = mpn_add_nc (scratch + n, scratch + n, dp, n, e); /* FIXME:e */
+ /* If the value was wrong (no carry), correct it (increment). */
+ e ^= CNST_LIMB (1);
+ MPN_INCR_U (ip, n, e);
+ }
+ }
+}